Mechanical and hydraulic absorbing means for a submersible pump system



Aug. 23, 1960 E. J. SCHAEFER MECHANICAL AND HYDRAULIC ABSORBING MEANS Filed Dec. 29, 1954 FOR A llll SUBMEIRSIBLEI PUMP SYSTEM 2 Sheets-Sheet 1 gi nllln Z 29 INVENTOR.

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BY m fi Mm )7 i0 49 6% Aug. 23, 1960 E. J. SCHAEFER MECHANICAL AND HYDRAULIC ABSORBING MEANS FOR A SUBMERSIBLE PUMP SYSTEM 2 Sheets-Sheet 2 Filed Dec. 29. 1954 United States Patent @fiiee MECHANICAL AND HYDRAULIC ABSORBING MEANS FOR A SUBMERSIBLE PUMP SYSTEM Edward J. Schaefer, Fort Wayne, Ind. Franklin Electric Co. Inc., 400 E. Spring St., Bluffton, Ind.)

Filed Dec. 29, 1954, Ser. No. 478,415

10 Claims. (Cl. 285-49) This invention relates to improvements in the mounting of pumps, particularly submersible pumps such as used in automatic pressure water systems and circulator pumps such as used in hot water heating systems.

An automatic pressure water system ordinarily comprises a motor driven pump arranged to pump water from a well and discharge it into an air cushioned pressure tank from which the water passes into various service lines. The pump is automatically started and stopped by a control switch responsive to the pressure in the tank or the pump discharge so that a bulk supply of water under pressure is maintained at all times in the tank and is ready for instant use upon withdrawal through the service lines. At the present time submersible pumps are coming into extensive use in such systems, particularly in residential locations where quiet operation of the pump is important. Although a submersible pump is normally characterized by a relatively quiet operation, eg as compared with an installation where the pump and motor are mounted above ground and adjacent the pressure tank, it is recognized that occasional complaints of noisy operation are received. Therefore, it is highly desirable to eliminate every possible source of noise. Complaints of noisy operation from submersible pump installations usually arise where the well is rather close to a dwelling and the pipe from the pump emerges from the well casing close to the tank and is connected rigidly with the tank. In this situation any noise from the pump is transmitted through the discharge piping to the pressure tank at the ground level which acts as a noise amplifier.

In hot water heating systems or the like a motor-pump unit is ordinarily interposed directly in one of the water circulation lines so that vibrations emanating from the motor or the pump are readily transmitted throughout the entire system including the individual radiators or heating units. Obviously, noisy operation in such a heating system is even more intolerable than in an externally located water system.

The sources of noise in a pump of the foregoing character may generally be divided into two categories. In the first place, the motor of the usual small size pump is of the single phase type. As is well known, the torque in the shaft of a single phase motor is not uniform but instead varies cyclically at twice the frequency of the electrical supply. Thus, in the case of a 60 cycle supply line, the torque of the motor instead of being uniform will pulsate at a frequency of 120 cycles. Since the rotor torque reacts against the stator of the motor, there will be a corresponding tendency for the stator to vibrate torsionally at the same frequency of 120 cycles per second. In addition to the foregoing electrical phenomenon as a source of noise, various mechanical disturbances such as unbalance of the pump impellers and lack of symmetry in the various pump stages may also give rise to water pulsations or other hydraulic vibrations which are transmitted through the water in the piping and end up as an audible noise which may sometimes be of an offensive magnitude.

Accordingly, it is a primary object in my invention to provide novel means for minimizing or substantially eliminating noise in the operation of a pump.

A further object of the invention is to provide novel means in a submersible pump system for retarding or preventing the transmission of noise and vibrations from the pump unit through the piping to the ground level.

Another object of the invention is to provide novel means in a circulator motor-pump unit for retarding or preventing transmission of noise and vibrations from the motor-pump unit throughout the circulating system.

Still another object of the invention is to provide novel resilient mounting means for a pump which counteracts noisy operation of the pump.

An additional object of the invention is to provide a novel combination of a pump, piping connected to the pump, and novel resilient mounting and fluid conduit means interposed between the pump and the piping for reducing the transmission of noise.

Other objects and advantages of the invention will become apparent from the subsequent detailed description taken in conjunction with the accompanying drawing, wherein:

Fig. 1 is a fragmentary vertical sectional view of a submersible pump unit including in elevation a pump mounting comprising one specific embodiment of the invention;

Fig. 2 is an enlarged vertical sectional view of the mounting device shown in Fig. 1;

Fig. 3 is a horizontal sectional view taken substantially along the line 33 of Fig. 2;

Fig. 4 is a view similar to Fig. 2 but showing a modified form of the invention;

Fig. 5 is a transverse sectional view taken along the line 55 of Fig. 4;

Fig. 6 is a side elevational view partially in section of a circulator motor-pump unit embodying the principles of the invention; and

Figs. 7 and 8 are fragmentary sectional views showing mod'mcations of the mounting means in Fig. 6.

As hereinbefore described, there are two principal types of vibrations which can be transmitted from a pump unit of the type here involved: (1) torsional or other vibrations emanating from the motor of the pump unit and transmitted mechanically through the connected piping, and (2) water pulsations or hydraulic vibrations arising from mechanical disturbances, such as cyclical variations in pump speed or vibrations due to an unbalanced pump impeller, and transmitted primarily through the water column in the outlet piping. My invention, broadly speaking, comprises a resilient mounting device which also conducts fluid and is interposed between the pump and the connecting piping for the purpose of absorbing both mechanical and hydraulic vibrations and substantially preventing both types of noise transmission. As will hereinafter appear, the device preferably has incor porated in it two cushioning means, one of which is effective primarily in absorbing mechanical vibrations, both torsional and vertical, transmitted from the pump unit through the piping and the other of which is specially designed to minimize or damp water pulsations or hydraulic vibrations arising from the causes hereinbefore described. The combined effect is such that extremely quiet operation of the pump unit is obtained.

Referring first to Fig. 1 of the drawings, a submersible pump unit of a commercially available type is shown fragmentarily and includes a motor section 10 and a multiple stage centrifugal pump section 11 operatively connected to the motor 10. A water intake having an Patented Aug. 23, 196.0

. sections.

inlet screen 12 is provided between the motor and pump A check valve 13 of a well known type is mounted at the upper end of the casing of the unit adjacent the pump outlet. Inasmuch as the structural details of the submersible motor-pump unit do not constitute any part of the present invention, no further description of this portion of the structure is believed to be necessary.

The motor-pump unit has a threaded outlet stub 14 which is normally connected to the outlet or discharge piping 16 which extends upwardly to the ground level. However, as shown in Fig. 1, a resilient mounting device 17 comprising oneembodiment of the invention is interposed between the outlet stub 14 and the piping 16 for preventing transmission of noise-producing vibrations While at the same time providing a fluid conduit means.

Referring now to Figs. 2 and 3, the pump mounting device 17 comprises a tubular outer housing or casing 18 having an enlarged diameter lower end portion and a reduced diameter internally threaded tubular extension 19 at its upper end, the outlet piping 16 being threadedly attached to this extension 19. Resiliently mounted within the housing 18 is a coaxial tube assembly consisting of a relatively short tubular member 21 having firmly bonded thereto an annular resilient sleeve 22 of rubber or the like and an outermost metal bushing 23 which is also firmly bonded to the rubber sleeve 22. In other words, the members 21, 22, and 23 are bonded together as .a unitary assembly with the rubber sleeve 22 interposed concentrically between the inner tube 21 and the outer bushing 23. The bushing 23 has a tight frictional press fit within the housing 18, and a circumferential shoulder 24 is provided at the interior of the housing 18 for receiving the upper axial end of the bushing 23 in seated relation thereagainst. A retainer ring 25 is fitted in a circumferential groove 26 adjacentthe lower end of the housing 18 for engaging and supporting the lower axial end of the bushing 23 and thereby firmly retaining the tube assembly 21--2223 in position in the housing 18. The lower axial end of the rubber sleeve 22 is cut away, as at 27, in order to accommodate the ring 25. By this arrangement it will be seen that the tubular member 21 extends coaxially with the housing 18 and the lower end of the tubular member 21 projects downwardly below the housing 18 and is threadedly secured to the outlet stub 14 of the motor-pump unit.

Thus, the housing 18 is rigidly mounted on the outlet piping 16 and the tubular member 21 which extends concentrically into the housing 18 is rigidly attached to the pump unit. However, the interconnection between the housing 18' and the tubular member 21 is through the medium of the resilient rubber sleeve 22 so that all torsional and even longitudinal or axial vibrations of the motor-pump unit which might possibly be transmitted to the tubular member 21 are cushioned or damped by the intervening rubber sleeve 22 and transmission thereof through the housing 18 to the outlet piping 16 is effectively prevented. 'Of course, it will be understood that the rubber-metal bond between the members 21, 22, and 23 is strong enough to withstand any force or load which may be imposed thereon. For example, the entire reaction torque of the suspended motor-pump unit relative to the fixed piping 16 is taken up by the sleeve 22 to prevent the unit from rotating. In addition, the tight press fit of the bushing 23 in the housing 18 provides a water tight seal 'so that outlet water from the pump unit 11 may pass directly through the outlet stub 14, the tubular member 21 and attached housing 18, and thence into the outlet piping 16 without leakage.

Although, as described above, the resilient cushioning sleeve 22 absorbs mechanical vibrations, both torsional and longitudinal or axial, which might otherwise be transmitted through the outlet piping, it will be evident that transmission'of hydraulic vibrations through the water cannot be stopped by the sleeve 22. In order to insure efiective cushioning action against water pulsation or other types of hydraulic vibrations, I also provide a separate resilient compressible cushioning element which, in this instance, comprises a length of hollow rubber tubing 28 sealed at both ends by a pair of rubber plugs 29 and coiled in the shape of a ring. As a matter of structural convenience, the ring shaped form of the tube 28 permits the tube to be disposed in the annular space between the housing 18 and the tubular member 21 so as to be out of the path of water flowupper end of the rubber sleeve 22 so that the ring 28 is not pinched when the sleeve 22 undergoes slight axial deflection due to the weight of the pump unit and hydraulic pressure. The hollow ring 28 is filled with a compressible gas such as air or the like in order to provide the desired compressibility or resilient cushioning action. However, it has been found that over a period of time and under relatively high water pressure the air may leak out of the rubber tube and the tube loses its resilience. To overcome this difiiculty an internal spacer or skeletal structure is preferably provided for the tube which permits the tubular rubber wall to expand or stretch inwardly under external hydraulic pressure. As shown in the drawing, an elongated coil spring 30 is disposed within the tube 28 so that, instead of the tube collapsing and merely compressing the confined air as the cushioning medium, the rubber wall of the tube stretches inwardly between the turns of the spring to provide the desired resilient action. There is also a slight axial contraction of the spring 30 which provides added resilience and cushioning action. Instead of a wire spring, I may also utilize other types of internal core structure such as a corrugated rubber filler or even an internal rib structure integral with the rub ber tube 28.

By the provision of the generally toroidal or doughnut shaped resilient cushioning ring 28, any hydraulic vibrations or pulsations which may be imparted to the water from the pump unit will be transmitted to the ring 28 and effectively damped or absorbed by compression of the gas contained therein or by stretching of the tubular rubber wall or both. In other words, the ring 28 preferentially absorbs the water pulsations or vibrations closely adjacent the source thereof and the inertia of the water column in the outlet piping above is sufiicient so that there is little if any transmission of water pulsations to tln's column of water.

As a safety precaution in case the bond between the rubber sleeve 22 and the members 21 and 23 should ever fail, a stop washer 31 is mounted around the tubular member 21 above the ring 28 and is held in place by a retaining ring 32 fitted in a groove 33 in the member 21. In the event of a bond failure, the stop washer 31 would seat against the upper end of the bushing 23 and prevent the pump unit suspended on the member 21 from falling into the well.

In order to facilitate installation of the resilient mounting means 17, the upper or inner end of the tubular member 21 is provided with a plurality of endwise slots 34 (Fig. 3), two such slots being shown in this instance. A pair of radially extending ribs or lugs 36 project integrally from the wall of the housing 18 and extend into the slots 34, the ribs 36 being narrower than the slots 34 and normally being spaced from the side edges of the slots as best seen in Fig. 3. However, when the device is being attached to the discharge piping 16 and the pump outlet stub 14 by rotary tightening of the threaded connections, the ribs 36 are rotatably shifted into sidewise engagement with the edges of the slots 34 by the limited 3 yielding action of the rubber sleeve 22. As a result, there is temporary rigid abutment and rigid rotary driving engagement between the respective tubular members 18 and 21 of the mounting device so that the metal-rubber bond between the rubber sleeve 22 and the metal elements 21 and 23 is not disrupted or subjected to undue strain. After the threaded connections of the unit 17 with the pump outlet 14 and the discharge piping 16 have been completely tightened, the natural resiliency of the rubber sleeve 22 allows the parts of the device 17 to return to the position shown in Fig. 3 wherein the ribs 36 are in spaced relation from the side edges of the slots 34.

In Figs. 4 and 5, I show a modification of the resilient mounting device whereby both the mechanical and hydraulic cushioning means are combined in a single unitary structure. The parts of the structure which are substantially the same as in Fig. 2 have been given the same reference numerals. Thus, the tubular housing 13 with the telescopically received tubular member 21 is substantially the same structural arrangement heretofore described, including the stop washer 31 and the retaining rings 25 and 32. However, the resilient sleeve means interconnecting the tubular members 18 and 21 differs somewhat from the arrangement shown in Fig. 2. In this case a rubber sleeve 37 is firmly bonded between a pair of concentric inner and outer tubular metal sleeves 38 and 39, the latter having a rigid press fit with the tubular members 21 and 18, respectively. The rubber sleeve 37 accomplishes the same mechanical cushioning effect as before whereby to retard transmission of mechanical vibrations from the tubular member 21 to the member 18. However, the separate hydraulic cushion ring 28 of Fig. 2 has been entirely omitted and in its place a plurality of axially extending pockets or holes 41 are molded integrally in the upper end of the rubber sleeve 37, these pockets 41 being covered over by a thin integral rubber film or wall 42. The pockets 41 are preferably filled with air. Inasmuch as the covering or rubber wall 42 is in direct fluid communication with the discharge fluid passing through the mounting device, it will be evident that any hydraulic pulsations in the pumped fluid will be transmitted directly to the elastic rubber covering film 42 and the latter will stretch inwardly into the pockets 41. The resilient distortion of the wall 42, together with the compression of the air cushion contained in the multiple pockets 41, or both, provide the required hydraulic cushioning action without the necessity of a separate cushioning element.

In Fig. 6 the invention is illustrated in connection with a circulator motor-pump unit of the type used in hot water heating systems or the like. The unit comprises a central motor section 43 and a pair of end bell sections and 46 one of which contains a rotary pump (not shown) connected to the motor. An elongated manifold 47 provides fluid communication between the end bell sections 44 and 45 and is spaced laterally with respect to the motor section 43, as more fully described in my co pending application Serial No. 249,565, filed October 3, 1951, now patent No. 2,731,918.

At each end of the motor-pump unit a coupling means 48 is provided for connecting the unit in a pipe line 49. In this instance, both of the coupling devices 48 are identical and only one will be described in detail. A tubular projection 51 extends from each of the end bell sections of the motor-pump unit and is received in coaxial telescopic relation within an enlarged diameter tubular portion 52 of a generally cup-shaped connector 53 secured to the pipe 49. The tubular portions 51 and 52 are interconnected by means of a resilient rubber sleeve 54 having metal sleeves 56 and 57 firmly bonded to the inner and outer peripheries thereof. The surrounding metal sleeves 56 and 57 have a rigid press fit at the inner bore of the tubular member 52 and at the exterior of the tubular projection 51., respectively. Suitable radial shoulder portions, as at 58 and 59, are provided on the memd bers 51 and 52 for axially engaging the metal sleeves of the rubber connector 54. The rubber sleeve 54 is of relatively short axial extent whereby to provide an annular clearance space 61 between the telescopically fitted members 51 and 52, and a resilient rubber ring element 62 with an internal spring 63 is disposed in this space 61. The ring means 6263 is identical with the ring means 2830 heretofore described in connection with Fig. 2,

and the inner axial end of the tubular projection 51 is cut away, as at 64, for providing more space for the ring member. On the basis of the same operating principles heretofore described, it will be understood that the resilient rubber sleeve 54 functions as a mechanical cushion to prevent transmission of mechanical vibrations through the pipe 49 whereas the resilient ring means 6263 functions as a hydraulic cushion to prevent transmission of water pulsations through the fluid in the pipe 49.

In Fig. 7 a modification of the connecting device 48 of Fig. 6 is shown. In this instance, the separate hydraulic cushion 62 63 has been omitted and the rubber sleeve, designated at 66, is provided with a plurality of integral axial bores or pockets 67 in the same general manner as heretofore described in connection with Figs. 4 and 5. However, the pockets 67 are completely open to the pumped fluid at the inner axial end of the sleeve 66, and the outer axial ends of the openings 67 are covered over with a thin rubber wall or film 68 which is adapted to expand outwardly against atmospheric pressure as required to absorb hydraulic pulsations in the pumped fluid.

In the event that the pumped fluid is at relatively high pressures, the thin wall 68 shown in Fig. 7 may not be strong enough to accommodate the large pressure differential between the pumped fluid and external atmospheric pressure. In Fig. 8, this difficulty is overcome by providing a flat annular ring 69 of relatively thicker rubber or other resilient material which overlies the inner axial ends of the openings 67. With this arrangement, the pockets 67 may be filled with air as before and the hydraulic cushioning effect is obtained by expansion of the annular diaphragm 69 into the pockets 67 or compression of the air contained in the pockets 67, or both. Of course, the thin rubber film as at the outer axial end of the sleeve 66 may also distort if necessary to accomrnodate hydraulic pulsations.

From the foregoing, it will be seen that my invention provides a simple and relatively inexpensive unitary device which can easily be interposed between a pump unit and its piping for cushioning and substantially preventing transmission of both mechanical and hydraulic vibrations. The mounting device can readily be manufactured in various pipe sizes as required and is easily adapted for use with any type of submersible pump, circulator pump, or the like so that no changes in pump design are necessitated.

Although the invention has been described with particular reference to certain specific structural embodiments thereof, it will be appreciated that various modifications and equivalent structures may be resorted to without departing from the scope of the invention as defined in the appended claims.

I claim:

1. Resilient mounting means for a pump and motor unit supported vertically in line by the piping for the pump, said mounting means comprising a pair of coaxial tubular members, one telescoped within the other to provide a fluid passage therethrough, said members being radially spaced apart at their overlapping ends forming a cavity open at one of its ends, one of said members being adapted to be secured to the pump and the other being adapted to be secured to the piping, resilient cushion means acting in shear interposed concentrically in the open end of said cavity and immovably secured to the adjacent walls of said members to absorb vertical and rotational shock between said members, and .hollow core substantially annular resilient means interposed concentrically in said cavity between said adjacentwalls inwardly of said cushion means from said open end, said cavity being in flow communication with said passage to subject said annular means to fluid under pressure from the pump, said annular means having means within the core thereof to continually exert an outward force on the walls thereof when subjected to said fluid pressure, thereby absorbing and damping fl-uid pulsations by a stretching action to vary the fluid volume within said cavity.

2. Mounting means according to claim 1 in which said cushion means is a resilient sleeve and said annular means comprises a portion of said sleeve, said portion having a plurality of circumferentially spaced pockets covered by a stretchable film of resilient material.

3. Mounting means according to claim 1 further characterized in that said members are provided with coacting abutment means normally disengaged but adapted to move into rigid engagement for limiting the extent of said relative rotary movement between said members.

4. Mounting means according to claim 1 further characterized in that said cushion means is an annular rubber sleeve having its inner periphery bonded to the outer wall of the inner member.

5. Mounting means according to claim 4 further characterized in that axial retainer means is provided between the outer member and the opposite axial ends of said sleeve for holding the latter in fixed relation axially of said outer member.

6. Mounting means according to claim 4 further characterized in that said rubber sleeve has its outer periphery bonded to the inside wall of a metal bushing, said bushing having a tight press fit within said outer member.

7. Mounting means according to claim 1 further characterized in that said annular means is separate from said cushion means and inwardly spaced therefrom in said cavity.

8. Mounting means according to claim 1 further characterized in that said annular means comprises an elongated hollow tube sealed at both ends and wrapped around the inner of said members in said cavity.

9. Mounting means according to claim 8 further characterized in that said tube contains an elongated coil spring, the wall of said tube being stretchable inwardly between the turns of the spring for damping hydraulic pulsations.

10. Mounting means according to claim '1 further characterized in that one of said members is provided with safety stop means for preventing separation of said members in the event the connection between said members through said cushion means fails.

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